Pretreatment effect of Cu feedstock on cold-sprayed coatings

Powder properties of the feedstock used for spray coatings, especially cold-spray coatings, have an influence on the coating properties such as deposition efficiency, morphology and hardness. The effects of pretreatment on Cu feedstock with dendritic morphologies used for cold spraying were investigated. The Cu powders were pretreated into air and vacuum in the temperature range of 50–200 °C at dwell times of 1 and 6 h. The deposition efficiency of the air-annealed feedstock shows an initial increase due to the stress relaxation till the oxidation begins and prevails in bringing about drop in the efficiency. The coatings produced from the vacuum-annealed feedstock had much higher deposition efficiency than the air-annealed feedstock, resulting from the combined effect of stress relaxation and reduction of Cu. Therefore, it was confirmed that the feedstock properties modified by a pretreatment had a significant influence on the properties of cold-sprayed coatings.